## Saturday, August 4, 2012

### Birthdays - plural, because why have just one?

I was born on the third day of August.  This year, as with every year, that fell on August third, yesterday.

I was born, and I did not know this so I had to look it up*, on the first Saturday in August.  Which this year falls on August 4th, today.

I was born on the third day after the second full moon after the summer solstice.  Which this year falls on August 4th, that's boring, I've already got an August 4th.

I was born on 10 K'ib'.  This year that falls on August 21st, and some years (not this year) it falls twice.

I was born on 14 Xul.  This year that fell on July 27th.

And, weirdly, as I pick calendars for their disconnection with our own, I'm getting a fair number of August 4ths.

I was born on 16 Dhū al-Qiʿda, which this year falls on October 2nd I'm told.  That's more like the variation I was expecting with certain other things.

Which is sort of the point of this.  "Falls on" implies a certain randomness because there is a certain randomness.  Solar calendars will tend to group things together so sticking with them will never get me far off from August 3rd, but with the right calendar any day could be one's birthday.  And with so many calendars already out there, there are several days for which one can make the argument, "It's my birthday."

Today might be one of your birthdays, without you even knowing it.

When were you born?  Don't feel restricted to the 6 ways I answered the question for myself above.

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I'd actually like to convert to Venusian or Martian dates (solar calendar, nothing complicated) but I have no idea how to do that.  It certainly should be possible.

And then there's a question of, there are 12 months in the year, if we're going with day of the month, why not 12 birthdays a year?

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* That's true of everything after this point, which given that I'm not going for perfection here means some of these things might be wrong.

1. The converter I found said I was born on the 30th of Cheshvan, but it didn't make clear whether that was before or after sunset. I suspect it's before, and as I was born after sunset my birthday is in fact the 1st of Kislev. (Which I think has a much better sound to it. And it's the month that Hanukkah is (mostly) in.)

Hang on. I can't read the Hebrew on my naming certificate, but perhaps with some assistance from Wikipedia and maybe Google Translate... Be right back.
[...]
Okay, so that word in the middle of the birthdate bit is definitely "Kislev". Looks like this year the first of Kislev is November 15-16th. Closer than I was expecting, but not quite the same.

The second Sunday in November (which I did not have to look up) is the 11th, which is the same as my maternal grandmother's standard date. (They had Veterans' Day parades in the patch of space-time she grew up in. When she was little her dad would take her to the parades and tell her they were for her.)

I was born, and I did not know this so I had to look it up, on the first Saturday in August.

Which makes you...twenty-seven? (Thirty-eight* is too old, I think twenty-one is too young, which leaves twenty-seven.)

*Looks like the 1980 leap day caused August 3rd to skip Saturday that rotation, so thirty-eight is the next oldest.

I was born on 10 K'ib'. This year that falls on August 21st, and some years (not this year) it falls twice.

I was born on 14 Xul. This year that fell on July 27th.

How did you go about calculating these?

And then there's a question of, there are 12 months in the year, if we're going with day of the month, why not 12 birthdays a year?

We celebrate my parents' lunaversary every month except June, when it's an anniversary instead. Lunaversaries are celebrated by going out to dinner, anniversaries by the exchange of presents between spouses and the eating of tuna subs in memory of their first dinner as a married couple. (I don't like tuna subs, so I think the lunaversaries are better.)

2. Which makes you...twenty-seven?

Yes.

How did you go about calculating these?

Through the first thing I found on google, which is here.

And it may actually be the third thing I found on google, which makes it weird since I appear to have skipped the first two results without looking at them.

Anyway, Gregorian to Mayan got me the two calendars, though it took me a bit to figure out what I was seeing because it gives the long count date which is written as five places of Long Count then the Tzolk'in date (two places), then the Haab' date (two places), then another place that I don't even know what it is.

Then I wanted to use the same converter to get the this year dates, which turned out to be somewhat more difficult than expected because it doesn't have a converter for that. So I used the Tzolk'in position and Haab' position things to find out both how many days into each year my birthday was, and how many days into the year today was (using Gregorian to Mayan to get today's date.)

At which point I did some math to figure out the dates of this year, and then used the Gregorian to Mayan converter again to check that I did the math right.

3. The Jewish Calendar is lunisolar, isn't it, which means it won't be too far away from the Gregorian. I must check this for myself.

(I'd like to learn more about calendars. My favourite so far is the elegantly simply Shire Calendar.)

TRiG.

4. For a few of us, there's another way to mark birthdays - we were born on a holiday. For example, I was born on Father's Day, so I could consider "Father's Day," whenever in June it falls, to be my birthday.

5. The Jewish calendar is lunar with extra months added every so often to keep it roughly aligned with the seasons. (Otherwise you end up with harvest festivals in mid-winter).

As for Venusian/Martian dates - as far as I know, there's no such thing. Sure, we know the length of the years, but defining a calendar requires, at a minimum, defining a starting point, and no one has ever bothered for Venus/Mars. (And of course months based on moons are impossible for Venus - no moon - and impractical for Mars - Deimos orbits in a little over 30 hours, Phobos less than eight!)

1. Dates would require various decisions involving actually making a calendar, but what a solar calendar attempts to approximate is the seasons, as determined by the position in the orbit with respect to the axial tilt.

That should be something that you can determine without creating a calendar, and determine the recurrence of, and whenever it recurs you say, "It's my Venusian\Martian birthday."

That's my thinking anyway.

2. In that case you could take the orbital period as the "year" and you'd be close to being right. (A spreadsheet will be able to handle the date calculations to convert N * local-year-in-days to an actual Earthbound date.)

6. The closest thing to a standard for Mars is probably the Darian calendar: https://en.wikipedia.org/wiki/Darian_calendar . It has its problems, but it's the one people have heard of.

Personally I like Unixtime (seconds since 1/Jan/1970). A small celebration every 10,000,000 seconds gives you slightly more than three per year; or every 2^25 seconds (the very memorable, to me, 33,554,432) is a year plus about 23 days.

7. Well, in my family we tend to celebrate birthdays two or three times. There's Actual (Gregorian) Date Birthday, upon which people sing to you, usually over the phone. There's Birthday Party Day, upon which you eat cake and receive presents. There's Birthday Party (Observed) or Secondary Party Day, for school friends if your birthday is during the summer, as everyone's but mine is, and people who couldn't make the other party (and vice versa, as in, hopefully everyone you want to invite can make one of the two). Of course Mr. Lonespark has Actual Date Birthday (Observed) when it isn't Leap Year...

For YuleBaby we may end up celebrating either Half Birthday in June or Rescheduled Birthday in, like, October, to get away from Christmas/Yule/assorted other winter celebrations/vacations/busyness.

1. There's one family I know--who are very busy and many of their friends (not us) are also very busy--who have been known to delay birthday parties for over four months until a date occurs that both they and a reasonable percentage of their potential guests can make.

8. I used to dabble with the idea of celebrating my saint's day, which would be 6th December. I'm not sure whether it's an advantage or a disadvantage that plenty of other people celebrate that anyway. Now I celebrate the anniversary of my name change - 22nd May - on the grounds that the beginning of transition is a kind of rebirth. Also, it's seven months after (or five months before) the anniversary of my initial birth, and spreading these things evenly through the year is a big plus for me.